6 Big Questions for the King of Data Storage

Oct 1, 2009

Mark Kryder, a professor at Carnegie Mellon's college of Electrical and Computer Engineering, is a legend in the world of computer capacity (click here for more on that underappreciated universe). He's most famous for his prediction about the exponential growth of hard drives, which is an analog to Intel co-founder Gordon Moore's famous law about computer processors. We contacted Kryder at the Perpendicular Magnetic Recording Conference in Tokyo to ask him a few questions about the future of the hard drive. —Glenn Derene

About how much does hard-drive capacity increase year to year?
The areal density on hard drives and therefore the capacity is currently increasing at about 40 percent per year, and I believe this will continue for the foreseeable future.

What do we need these big hard drives for now?
There is demand for higher capacity in almost all segments of the disk-drive business. Personal video recorders and drives for servers require the highest capacities. As we are just beginning the transition to HDTV, these demands are about to increase dramatically. Recent market studies by IDC have indicated that the supply of disk-drive capacity is lagging demand.

What do you see as the next great hard-drive hog?
HDTV.

In the laptop market, there seems to be an encroachment of flash memory SSDs into the hard-disk drive space. Will flash capacities eventually catch or eclipse HDDs?
It is a misstatement to say flash is encroaching upon hard drives. Until the iPod put hard drives in digital audio players, that market was totally dominated by flash.

However, it also wasn't a very exciting business. When Apple put hard drives into the iPod, they suddenly provided enough capacity to make digital audio players an exciting market. Now, as Flash has increased its capacity and lowered its cost, it has begun to reclaim some of the territory it lost, but not at the expense of hard drives.

On the contrary, all the flash applications require backup and servers to send audio songs, pictures or whatever over the Internet. And all those applications are fulfilled by hard drives, because they offer much higher capacities and much lower cost per gigabyte. The fact that hard drives are cheap to make means that there always has been a capacity point below which various solid-state memories could offer a lower-cost device. Since storage density for both hard drives and solid state memory devices always increases, that capacity point also moves upward. It should also be pointed out that flash and HDDs are actually complementary. Seagate, for instance, has recently announced its hybrid hard-drive product in which a flash cache provides faster read-access time and lower power operation.

What about online storage? As ISPs start to offer fiber to the home with immense bandwidth, do you anticipate that people will simply migrate to remote storage systems such as Xdrive or box.net?
There is no question that networking is going to improve, and in the future, we will all have servers in our home for our personal digital information. But I believe we will always want our own copy of our personal information. If it only costs you $100 to store all your own personal information so you can always have it accessible and take it with you on a vacation, wouldn't you do it?

Is Hitachi's CPP-GMR going to be the only technology pushing capacities to the 4TB mark? What else is under development?
We have all been predicting that perpendicular recording would reach roughly 1 terabit per square inch (which is the areal density that will provide 4 terabytes in a single drive) around 2011. The challenge is to get beyond 1 Tbit per square inch.

The CPP-GMR head has been in research and development in most companies for well over a decade, and it has been recognized for many years that CPP-GMR will be necessary to go beyond a certain areal density around 1 Tbit per square inch. In my view, this announcement is thus much more important for going to 10 Tbits per square inch than to 1 Tbit per square inch, because CPP-GMR heads scale much better than tunneling magnetoresistive heads, which are in current products.

However, to get to 10 Tbits per square inch will require a drastic change in recording technology. Heat-Assisted Magnetic Recording and Bit-Patterned Media are technologies that are under development to make that happen. I am the technical director of the Extremely High Density Recording program of the Information Storage Industry Consortium, which Hitachi, Seagate, Western Digital and Samsung all currently support, and we are currently working on this 10-terabits-per-square-inch goal, which would enable a 40-terabyte hard drive.

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